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TOPIC: Underlayment

Metal Roof and Underlayment

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I live in Florida by a salt water canal. I have estimates on a 5v gavaloom and standing seam is about $10,000 more. What is the best cost effective metal roof? My second question is what is the best underlayment for a metal roof: felt,sysnthetic,self adhering or a combination of both? Thank you for your assistance in this matter.
Guest User

1/12/2005
As an association we are restricted in our comments on costing. I can tell you that Galvalume is a meterial not a roofing system. It is a metalic coated alloy steel with Zinc and Aluminum with excellant corrosion resistant properties. Many roofing systems are made with this material in either bare or painted. If choosing bare thenask for the acrylic coated so that it does not stain during handling. Possibly you are comparing through fastened vertical rib and a standing seam vertical rib. There are many issues to consider. The first being that the product meets the Florida building code for your application. Check with the local building department to see what is required. Then the code also calls for ventilation. If it is a vaulted ceiling then it must have a minimum of 1" vented air space under the roofing. Choose a system that meets this need. Also give consideration to choosing and energy star system that will cut your unitilty bills for AC. As to underlayment, remember that you are deciding on a permenat roof system so an upgrade underlayment is best. It really depends on the slopeand configuration of the roof. Once you choose a product look up their FL product approval as it will dictate what underlayment must be used.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/13/2005
Both types as mentioned metal roofs meet Florida code plus others.My question" what is the best metal roof for the dollar cost?" Also on underlayments I have seen the self-adhering going on bare wood and self-adhering going on top of felt.I am confused as to what is the best method. Also is the Synthetic underlayment just as good? Thank You
Guest User

1/13/2005
To the best of my knowledge, virtually manufacturers of self-adhering underlayments all want their products over new decking. I like the synthetics but they do not play the same role as self-adhering products. They replace felt but not self-adhering products. As far as cost, we just cannot talk about price -- it is against our antitrust guidelines. Contact individual manufacturers direct and they will help you.
Guest User

1/14/2005
My neighbor is having a metal roof installed, they are applying the metal sheets directly to the old worn shingles without anything in between, is this a good thing? Will this roof have problems down the road, and what to look for? thank you J in Lakeland fl
Guest User

1/15/2005
I would always put an underlayment between the two. Otherwise, with expansion and contraction, the granules can damage the back side of the metal. (That said, the entire world undoubtedly does not agree with me as to the necessity of an underlayment in this case.)
Guest User

1/15/2005
Further to Todds response, the building codes call for an underlayment unless the product has been tested and approved without one. Always ask to see the product approval report which dictates how the product is to be installed in various new and reroof applications. If it does not have one, then that is an indication to watch out.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/17/2005
"To the best of my knowledge, virtually manufacturers of self-adhering underlayments all want their products over new decking." I see re roofs in Florida using the self-adhering underlayment with clay tile and metal. My neigbors roofer just used it under asphalt shingles is this wrong?. With hurricanes and their devastation this past year. People are looking for the best roofing materials..It seems that the metal roof held up the best but is it worth the big expense?
Guest User

1/17/2005
Florida has a number of weather issues and with Hurricanes comes flying debris, the worst being concrete tile projctiles. The high velocity wind areas required 5/8" minimum sheathing to stop the sheathing from being penetrated and the resulting decompresion of the home which then allows the roof system to change states. Concrete tiles absorb water and with winds the system leaks and requires a secondary membrane to stop the water. Most choose to use a mop down tarand felt underlayment or a self adhering the seals around the penetrations. Your neighbours with the asphalt shingles are taking extra prcautions in case the wind comes and blows the shingles off, they are protected. Quite possibly it may be required by their insurance company or even the building codes. Wwe had the equivolent of 1200 roofs that took direct hits in Jamaica, Bahamas and Florida this year and all survived with a little debris impact damage which was easily repired. Sounds like a good investment. Do it right and do it once. Give yourself piece of mind.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/18/2005
I have estimates on a 5v and standing seam. The standing seam from what I am told is the better roof as no screws are exposed to the elements.The standing seam is expensive. Is the standing seam harder to install? Just don't know why the additional cost.
Guest User

1/18/2005
There is substantially more metal in standing seam, due to the narrower panels and higher seams. Also, often, there will be difference in the coating and metal types and qualities. As far as labor, yes standing seam will take longer t install. Also, you're often dealing with longer panels which tends to add cost.
Guest User

1/18/2005
We are in the process of purchasing a new home. The home was built in November 2004, so is just over one year old. The inspection is being done as we speak and my husband called to state that there was a problem with the metal roof. It apparently has no underlayment (ie felt). Is this a problem that needs to be fixed and should prevent us from purchasing the property or is this alright. I would appreciate your input as soon as possible. Thanks!
Guest User

1/20/2005
You will need to track down and contact the manufacturer of the roofing installed on this home and get their opinion. They will want to know the full installation details -- decking or not, ventilation, insulation, vapor barrier, etv.
Guest User

1/20/2005
I currently have a screw down roof, and I'm looking at getting it replaced with a standing seam or shingles. A screw down metal roof requires IMO more maintanence than an ashpalt shingle roof here in TX. You need to constantly check the screws and make sure they are screwed in tight, but not too tight to destroy the neoprene washers or make a dent in the roof where water could collect. Due to the high heat here the roof moves around a lot and screws will come out. I've had so many minor leaks due to screws that I'd rather not ever deal with them again. Other than that and some pitch change issues the screw down has served me well. Just that having my existing roof repaired will cost the same as having a new asphalt shingle roof (30 yr) put on. To me the low maintanence of a standing seam is what attracts me.
Guest User

1/23/2005
Very interesting about the 5V roof in Texas with the screws becoming loose. Is the 5v panel screwed directly to the roof or 1 x 4 furring boards? In a conversation with a roofer he attaches the panels to the 1 x 4 furring boards to prevent condensation build up under the panels which makes sense to me. I have read that a metal roof can rot out from underneath the panel if not installed properly.Due to the high cost of standing seam. I can only afford 5V but am I looking for problems as noted by the reply from Texas? Also is a ridge vent necessary with a metal roof?
Guest User

1/24/2005
Always check with the manufacturer for instalation instructions. They should also have a product approval report which dictates how it can be installed over variious assemblies. If they do not support this then this is an indication. Also there are various metal substrates and paint systems. Don't be fooled thinking that all metal is the same. Watch you are not buying an agricultural panel. As to the screws, they must go into something solid or they will not hold as the metal expands and contracts. All roofs must be ventilated, not just metal and all roofs need underlayment unless tested otherwise.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/24/2005
I'm the one in TX with a screwdown. Mine is attached on 1x4 furring strips. I've never had a condensation problem and I don't have a ridge vent, however I have 4 gable vents and plenty of natural venting at the seams of the metal roof. If I decide to replace it with a standing seam metal roof, I'll still get a ridge vent. Good ventilation is essential and the cost is so small to add it. To be honest I'm right now leaning towards putting 30 year shingles, because I'm not sure I can justify the cost of the standing seam to myself. My reason for not getting another screw down is that If it ever leaks I'd rather be able to fix it myself than having to pay somebody to do it. I think I've had to maintain the screw down more on my screw down roof than I ever did on my old house with shingles. I'm sure a screwdown is fine for the first 5-10 years depending on movement, but eventually it will need to get the screws replaced and you also need to check them on a regular basis to make sure they've not backed out due to the expansion and contraction of the metal. If I get shingles I will likely get a screw down metal on the back porch area as it is a low slope. Also it is not over the interior of the house. It is also a smaller area to keep up with the screws.
Guest User

1/24/2005
Like any roofing products there are various grades of performance and with contractors there are various grades of workmanship. Pick the lows of each and you can have a recipe for disaster. Unfortunately many people (consumers and Contractors) go to a retail yard and order sheets of steel not knowing what they get and how to install it properly. Always ask the manufature for their recomendations and to see their product approval report which indicates that it has been tested and approved to meet the building code. If either is lacking then that is an indication. If someone installs an through fastened panel, there needs to be attention to detail. The right diameter, length and seat on the screws are important and they also must be installed not overtightened to allow the sheets to move. The longer the sheets the more expansion and contraction has an effect so the location of the screws become more important. I have never heard of screws backing out that were installed correctly. If one installs too long a screw in wet lumber, then the screw will sit proud as the lumber shrinks, giving you the effect that they came loose. You may have a condensation problem and not know it in that the lumber is absorbing humidity nad expanding/contracting to some degree. We have a numberof member manufacturers that do have proper details to install through fastened panels. Check them out and see if yours was to the same spec.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/25/2005
Lena, Another question for ya? Are the screws in the ridge portion of the panel or the flat portion? I was told that the panels should be screwed down in the flat portion by the manufacturer. Yet the homes in my area with 5V have the screws in the ridge of the panel. The install of a metal roof requires a lot of research. Yet the roofers want do it their way..
Guest User

1/25/2005
Roy, I have some in both, flat portion is what I understand is correct too. Now mine has been on the back of the house for 25 years and the front for about 7 years, however they recommend here to rescrew or tighten every 6-9 years (depends on the seals on the screws). This seems about right from what I've seen. I've asked several of the roofers here too as I've looked at all the options for me and standing seam would be far superior, however it does come at a cost. Also even those that only want to sell me the screw down admits that it needs a bit more maintance than shingles around here. As far as screws backing out I don't mean they come out completely, but they do move out some and if the neoprene seal goes bad you have a leak ,especially if the screws are on the flat portions. I've had a real hard time finding some of them too. It is not always visible without really looking closely, and it is also something that shows up with time. I've been told by several of the roofing companies that mine is one of the better installs they've seen of a screw down. Just getting old and rusted in spots (outside not on the inside) and needs to be re-screwed. So the cost of fixing the leaks along with a re-screw and replacing some rusted parts puts me close to a new shingled roof.
Guest User

1/25/2005